While rummaging through my cabinets looking for some Tylenol, I started thinking about the drug delivery mechanism they use in the movie “Looper”: eye drops.
I would think eye drops would have terrible absorption. The cornea has no vasculature whatsoever, and while the sclera does, absorption would still be horrible, what little that gets absorbed would be completely diluted by the circulating through the body and then getting metabolized by the liver, and very little of it would actually be available to cross the blood-brain barrier.
Unless what they’re dropping into their eyes aren’t conventional pharmaceuticals, and are actually computer-programmable nano particles that invade into the vitreous and project all sorts of weird visual stimuli. (I thought about virus delivery systems, too, but it would take way too long for the virions to get absorbed prior to infecting the optic nerve and latching into the brain. It would be a feasible way to alter consciousness long-term, but it doesn’t seem like it would get much traction as a club drug.)